Companies can improve their fuel efficiency in many different ways. Several manuals have been published by government agencies, trade associations, magazines and oil companies providing advice on the broad array of measures that can be applied. At various times in the past, some measures have been hyped as offering a quantum leap in fuel efficiency only to disappoint hauliers that tried to implement them. A good example is the attachment of magnets to diesel engines supposedly to improve combustion efficiency and reduce the amount of unburnt fuel. As a government-sponsored report has pointed out, however, There is no evidence that even quite strong magnetic fields can cause ionization in gases or significantly influence combustion. Suppliers have produced little or no evidence that these types of fuel-saving device actually work (DfT, 2003: 4).
Many of the claims made for fuel economy measures rest on quite flimsy empirical evidence. Some years ago, the US governments Environmental Protection Agency tested 106 fuel-saving devices and found that only five indicated a statistically significant improvement in fuel economy without an increase in exhaust emissions (DfT, 2003: 4). These five related either to changing driver habits or improving the efficiency of air conditioning systems. (This finding on air conditioning cannot be directly extrapolated to other countries, such as the UK, where average summer temperatures are significantly lower than those in most of the United States.)
Another problem with checklists of fuel economy measures is that they often give the impression that all the savings are additive. Claims are often made that individual measures yield fuel savings of 13 per cent. In theory, if a haulier implemented 20 of these measures, it might cut its fuel consumption by 2060 per cent. Research in the United States, for example, has assessed the percentage fuel savings that an average trucker might achieve by applying a range of 10 measures (Ang-Olson and Schroeer, 2002) (Figure 11.1). These savings vary from under 1 per cent for automatic tyre inflation systems to almost 8 per cent for a reduction in maximum speed from 65 mph to 60 mph. If all these savings were cumulative, aggregate savings of 33 per cent might be achieved. In practice, this is unrealistic. Some measures, after all, are counteracting. For example, cutting maximum speed will reduce the effectiveness of improved trailer and tractor aerodynamics.
A fuel economy initiative should not, therefore, comprise a loose collection of measures. It is much more effective to integrate a specific set of measures into a well-structured programme tailored to the needs of particular operators. As part of its Freight Best Practice programme, for example, the UK government has developed a fuel management guide, which not only outlines some of the more promising fuel economy measures, but also sets out a management framework within which these measures can be implemented and their effects evaluated. The oil company Shell has also advocated a holistic approach to the whole issue of transport efficiency and has given this approach the brand name Fuel Stretch (Anon, 2006). Its programme comprises 25 fuel-saving tips, including advice on how to manage the programme.
It is very difficult to assess the overall potential for improving the average fuel efficiency of road haulage operations for several reasons:
Ø There are many different sources of efficiency improvement.
Ø There is a complex interaction between different types of improvement measure; in some cases there is mutual reinforcement while in others they are counteracting.
Ø There are often quite wide variations in the estimates of potential fuel savings from different sources.
Ø It is often unclear from what baseline potential savings are being calculated, particularly when they are generalized at an international level.
By benchmarking the fuel efficiency of fleets engaged in similar types of distribution operation, one can get a rough indication of potential savings given currently available technology. This is discussed in the next section.
